1. Field of the Invention
The present invention relates to an apparatus and method for anchoring suture to bone and, more specifically, to an apparatus and method for anchoring suture using a corkscrew suture anchor.
2. Description of the Related Art
When soft tissue becomes torn away from the bone, reattachment to the bone is necessary. Various devices, such as screws, staples, and sutures alone, have been used to secure soft tissue to bone. Recently, suture anchors have been developed for this purpose.
Among the suture anchors that have been developed, some are self-tapping and others are inserted into a pre-drilled hole. For example, U.S. Pat. No. 4,632,100 discloses a cylindrical suture anchor which includes a drill at a leading end (for boring a hole in a bone) and a flight of threads at a proximal end of the anchor for securing the anchor into the hole created by the drill. U.S. Pat. No. 5,370,662 discloses a self-tapping suture anchor having a flight of threads around a solid body. U.S. Pat. No. 5,156,616 discloses a similar suture anchor having an axial opening for holding a knotted piece of suture.
All of the above-noted suture anchors rely on a flight of threads disposed on the outer surface of a core to secure the anchor to the bone; all provide an easy, secure method of suture fixation in hard cortical bone.
Recent studies indicate, however, that the above-noted suture anchors may have problems related to adequate "pull-out" strength, especially in softer, cancellous bone. Thus, under certain conditions, these known suture anchors can pull out of the bone, requiring costly and difficult repair of the damage site. Moreover, installation of the above-described suture anchors results in a substantial loss of bone stock. Thus, during procedures that require removal or relocation of suture anchors, these types of suture anchors produce holes or defects which reduce bone strength and diminish the availability of specific fixation points.
Accordingly, a need exists for a suture anchor which can be secured in soft cancellous bone and does not displace a large amount of bone upon insertion.